Delta 45 Specifications download pdf (Page 14)

OPAMP

CLK

OPAMP

CLK

ADC12EU050

SNAS444I –JANUARY 2008–REVISED APRIL 2013

www.ti.com

Figure 6. SHA Input Stage

Figure 7. Continuous Time Sigma Delta Input Stage

INSTANT OVERLOAD RECOVERY

The ADC12EU050 features an overload handling system which provides instantaneous recovery from signals

driving the ADC inputs beyond the full-scale input range. The ADC can operate in two different modes. In the

default ADC mode (IOR mode off) a full-scale input range of 2.10 V

is supported, here the ADC operates with

some inherent overload recovery time, similar to a conventional ADC.

In the IOR mode, the ADC has a reduced 1.56 V

full scale input range, but provides a significant benefit in that

the ADC can now be driven by input voltages as high as 5 dB beyond the nominal full-scale (f

< 12MHz), that is

2.75 V

, and will recover instantaneously. In a number of applications this feature can help simplify input stage

design and manufacturing set-up and calibration. The ADC12EU050 recovers immediately from overload with no

missing codes and no settling time.

The proprietary strategy used within the ADC12EU050 uses high speed patented clamp techniques to limit the

input signal and keep it within the stable input range of the ADC. This process happens at a speed equivalent to

the on-chip over-sampling rate of 720MHz. The advantage of this system is that it responds immediately to out of

range signals. While the inputs are over-range the ADC outputs a full scale result. As the over-range input is

removed the ADC adjusts to the input signal level and is able to provide sampled data instantaneously. The

ADC’s behavior on emerging from overload is repeatable and independent of whether the input signal was

positive or negative going at the point of overload. The diagram below shows a 5dB overloaded input (2.75 V

versus 1.56 V

Full scale), with 240,000 sample periods overlaid. There is no ringing and recovery from

overload is instantaneous.

Product Folder Links: ADC12EU050

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Delta 45 Specifications Page 14